Platform - 1994 Eunos (luxury brand of Mazda) JC Cosmo (4th generation) Type SX
Original engine - 13b twin rotor, twin turbo Wankel engine
Original transmission - electronically controlled 4-speed automatic gearbox to approx 4.3:1 rear axle differential
Original kerb weight - approx 1550kg
Production number - 8,875
Why I chose this car to convert?
Because I had wanted one for a very long time and when one became available I couldn't pass the opportunity. It's a rare car and needed to be saved. The car came to me with no engine (rolling chassis) and when I began looking into the cost of finding and installing an original rotary engine it began to make more sense to convert to full electric instead since it would be a significant investment either way. The pros of restoring to original would be a higher future value in terms of investment due to correct originality. The pros of converting to EV would be use as a daily commuter and gaining EV conversion skills. The cons of restoring to petrol engine is that it would unusable for daily driving due to poor fuel economy. The cons of EV conversion are the complexity of the project and things outside of my ability.
Initially my plan was to use components from a Nissan Leaf: motor, inverter, battery pack and other misc. parts. The logic behind this is due to the availability. There aren't many EVs in this country (New Zealand) and things like Telsa are VERY rare and expensive. Nissan Leaf is by far the most common and most available to get hold of cheap from insurance auctions and the like. Obviously fitting a transverse FWD unit into a RWD platform is not ideal and I was facing the option of retro-fitting a manual gearbox (Cosmos never had a manual transmission) in order to get usable drive ratios, driving the driveshaft directly (which would cause final drive ratio issues as the rear diff of the Cosmo is 4.3:1 and the Leaf runs natively around 8.1:1), or modifying the rear subframe to accept the Leaf in transverse orientation (which would probably require extensive and irreversible engineering work).
My plans changed significantly once I found out about the Lexus GS450H transmission and the potential to chop off the ICE engine and run it completely in electric mode. This has been done successfully before in a 3 Series BMW and others on this forum are also working on their own conversions using this drive unit. The biggest appeal for this transmission in my project is the longitudinal layout which should fit within the drive tunnel of my car without significant work, and also the fact the GS450H transmission (type L110) has a 2 stage ratio in the rear for highway speeds. This transmission is different to the one in the IS350H which is lacking the 2 stage ratio, and different to the LS600H which has an additional transfer case at the rear for 4WD output to the front differential in that car.
The matching inverter from the GS450H would seem an obvious choice to drive the unit but this is where my limitations are. I have very little in the way of electronics ability and so find myself reliant on the continued work of smarter people on this forum to solve the control problems of this type of Toyota/Lexus setup. I'm agnostic about batteries and BMS. I expect to need around 40KWh to cover my daily commute without recharge.
. That would be my plan.